If you start using any of the mail back ends, they have the annoying habit of assuming that you want to read mail with them. This might not be unreasonable, but it might not be what you want.
If you set
nil, none of the back ends will ever attempt to read incoming
mail, which should help.
This might be too much, if, for instance, you are reading mail quite
nnml and just want to peek at some old (pre-Emacs
23) Rmail file you have stashed away with
nnbabyl. All back ends have
variables called back-end-
get-new-mail. If you want to disable
nnbabyl mail reading, you edit the virtual server for the
group to have a setting where
All the mail back ends will call
narrowed to the article to be saved before saving it when reading